Neurovascular lesions, such as aneurysms and arteriovenous malformations (AVMs), are insidious and unpredictable. They often go unnoticed until the occurrence of a catastrophic hemorrhage or stroke. Approximately 350,000 patients experience hemorrhage annually, resulting in permanent loss of motor function, seizures, and death. Current neurosurgical therapies are risky and often ineffective at removing the life-threatening condition. The purpose of this venture is to provide an innovative biomaterial for treating neurovascular lesions from inside the vessel (endovascular embolization) in order to significantly increase therapeutic effectiveness while minimizing the surgical risks. Preliminary studies have identified calcium alginate (ALGEL) as a potentially non-adhesive, injectable, mechanically stable, and biocompatible material for effective occlusion of vascular lesions. A preliminary comprehensive in vitro aneurysm model has been developed, utilizing documented and tested neurovascular modeling techniques, to test ALGEL injectability and occlusion stability. Techniques learned will then be utilized to occlude chronic aneurysm models in swine. Lastly, a final round of chronic AVM models will also be occluded. The goal of the continued animal experiments is to utilize our knowledge in vivo modeling to complete 6-month chronic AVM and 1-month aneurysm occlusion studies for determining the long-term ALGEL stability and biocompatibility. The outcomes of the proposed project will be a solid foundation for the eventual development of safer and more effective treatments for life threatening aneurysms and high-grade AVMs. More generally, alginate embolization may also prove useful for minimally invasive vascular therapy of other vessel areas as well, such as blocking blood flow to tumors, stopping pelvic bleeding, treating uterine fibroids, and occluding other peripheral vessel damage and lesions.